The present invention relates to a processing apparatus for applying a predetermined process to an object, and a processing system having the processing apparatus.
As the processing apparatus for applying a predetermined process (such as film formation, etching, oxidative diffusion) to a semiconductor wafer to form a semiconductor integrated circuit, a batch-type processing apparatus and a single-wafer processing apparatus are generally known. In the batch-type processing apparatus, a plurality of wafers stacked one upon the other with a predetermined pitch are processed at the same time. Whereas, in the single-wafer processing apparatus, wafers are processed one by one at high speed. As a size of the wafer increases from 6 to 8 inches or to 300 mm in diameter, the single-wafer processing apparatus tends to be used since the resultant film can be obtained uniformly.
The single-wafer processing apparatus such as a film formation apparatus has a cylindrical processing vessel capable of producing a vacuum therein, a table (susceptor) arranged horizontally within the processing vessel for mounting an object to be processed such as a semiconductor wafer thereon, a heater (or a heating lamp) arranged under the-table for heating the object mounted on the table, and a shower head arranged on a ceiling portion of the processing vessel so as to face the table. With this structure, a requisite gas is sprayed to the object from the shower head while heating the object (horizontally placed on the table) and maintaining it at a predetermined processing temperature by the heater. In this manner, a predetermined process including film formation can be applied to the object.
FIG. 14 shows a processing system having two single-wafer processing apparatuses 6 constructed as mentioned above. As shown in the figure, the processing system has a transfer chamber 4 having a foldable and rotatable transfer arm 2, a load-lock chamber 8 connected to the transfer chamber 4 with an openable gate valve G1 interposed between them, and a cassette chamber 10 connected to the load-lock chamber 8 with an openable gate valve G2 interposed between them. The cassette chamber 10 is used for loading a cassette which stores unprocessed objects into the system or unloading a cassette which stores processed objects from the system. To increase a processing efficiency, two processing apparatuses 6, 6 are connected to the transfer chamber 4 with openable gate valves G3, G4 interposed between them.
To maintain the transfer chamber 4 always at a predetermined vacuum, the load-lock chamber 8 is interchangeably set between an atmospheric pressure and a vacuum, repeatedly. More specifically, when the load-lock chamber 8 is-communicated with the cassette chamber 10 under atmospheric pressure, the load-lock chamber 8 is set at the atmospheric pressure while leaving the gate valves G1, G2 closed. Thereafter, the gate valve G2 is opened. On the other hand, when the load-lock chamber 8 is communicated with the transfer chamber 4 under vacuum, the load-lock chamber 8 is set at the same vacuum pressure as in the transfer chamber 4 while leaving the gate valves G1, G2 closed. Thereafter, the gate valve Gi is opened.
In the processing system constructed as mentioned above, a object such as a semiconductor wafer is taken out from a cassette within the cassette camber 10 in a horizontal posture, transported to the processing apparatus 6 within the system while maintaining the horizontal posture, and horizontally placed on the table within the processing apparatus 6. Therefore, each of the processing apparatus 6 and individual chambers 4, 8, 10 is designed in such a way that its foot print (its image projected on the floor surface) is larger than that of the object, in term of area. Consequently, with the increasing tendency in size of the object in recent years (for example, the size of the object (such as a semiconductor wafer) increases to 8 inches or to 300 mm in diameter), the foot prints of the processing apparatus 6 and individual chambers 4, 8, 10 are inevitably increased. As a result, the area of the processing system occupied in the clean room becomes quite large.
Since the manufacturing cost per unit area of the clean room is quite high, it is desired that the clean room must be used efficiently in consideration of the foot print. To attain this, the foot prints of the processing apparatus and the entire processing system including the processing apparatus, must be reduced as much as possible. Furthermore, in the single-wafer processing apparatus, a throughput is inevitably limited by an inherent feature of one-by-one wafer processing system.